Hip surgery systems and methods

ABSTRACT

Orthopedic systems and methods are provided for use in preparing joints for implants. Specifically, hip preparation systems and methods are disclosed which can include a surgical orientation device. The hip preparation systems and methods can be used, for example, to orient the hip during the procedure, determine the orientation of an anatomical plane or planes, and orient a prosthetic component or components.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. §119(e) to U.S.Provisional Patent Application No. 61/191,603, filed Sep. 10, 2008, andto U.S. Provisional Patent Application No. 61/226,668, filed Jul. 17,2009, each of which is incorporated in its entirety by reference herein.

BACKGROUND OF THE INVENTIONS

1. Field of the Inventions

The present application is directed to systems and methods for jointreplacement, in particular to systems and methods for hip jointreplacement which utilize a surgical orientation device or devices.

2. Description of the Related Art

Joint replacement procedures, including hip joint replacementprocedures, are commonly used to replace a patient's joint with aprosthetic joint component or components. Specifically, the hip jointoften requires replacement in the form of prosthetic components due tostrain, stress, wear, deformation, misalignment, and/or other conditionsin the joint. Prosthetic hip joint components can be designed toreplace, for example, an acetabular prosthetic socket in the hip and/ora femoral head.

Current systems and methods often use expensive, complex, bulky, and/ormassive computer navigation systems which require a computer orcomputers, as well as three dimensional imaging, to track a spatiallocation and/or movement of a surgical instrument or landmark in thehuman body. These systems are used generally to assist a user todetermine where in space a tool or landmark is located, and oftenrequire extensive training, cost, and room.

Where such complex and costly systems are not used, simple methods areused, such as “eyeballing” the alignment of a prosthetic acetabular cupor femoral broach. These simple methods are not sufficiently accurate toreliably align and place implant components and the bones to which suchcomponents are attached.

Correct positioning of surgical instruments and implants, as used in asurgical procedure with respect to the patient's anatomy, is thereforeoften an important factor in achieving a successful outcome. In certainorthopedic implant procedures, such as total hip replacement (THR) orarthroplasty, total knee arthroplasty (TKA), high tibial osteotomy(HTO), and total shoulder replacement (TSR), for example, the optimalorientation of the surgical implant can enhance initial function andlong term operability of the implant. A misaligned acetabular prostheticcup can lead to complications such as dislocation of the hip joint,decreased joint motion, joint pain, and hastened failure of the implant.

SUMMARY OF THE INVENTIONS

Accordingly, there is a lack of devices, systems and methods that can beused to accurately position components of prosthetic joints withoutoverly complicating the procedures, crowding the medical personnel,and/or burdening the physician or health-care facility with the greatcost of complex navigation systems. Thus, there is a need in the art forimproved systems and methods for obtaining accurate orientation ofsurgical instruments and implants during various orthopedic repair andreplacement procedures, including total hip replacement (“THR”).Furthermore, there is a need for such devices and methods to be simpleand easy to operate.

In accordance with at least one embodiment, an apparatus for preparing ahip joint can comprise a reference post having a distal end adapted tobe driven into a portion of a pelvic bone, a proximal end, and areference post body extending along a longitudinal axis between theproximal and distal ends, a coupling device disposed adjacent to theproximal end of the reference post adapted for connecting the referencepost body to a second surgical component, and an orientation sensorcoupled with the reference post.

In accordance with another embodiment, an apparatus for preparing a hipjoint can comprise a mounting structure having a first end adapted tosecure to a patient's anatomy and a second end disposed away from thefirst end, an elongate member having a first end and a second end, thefirst end of the elongate member adapted to connect to the second end ofthe mounting structure, a marking device coupled with the second end ofthe elongate member for visually indicating the position of ananatomical landmark during a procedure, and a surgical orientationdevice coupled with the elongate member for movement therealong formeasuring at least one of position and orientation along the elongatemember.

In accordance with another embodiment, an apparatus for assessing theorientation of an acetabular landmark or an acetabular implant cancomprise a handling device comprising a proximal end with a handle, adistal end, and an elongate member extending therebetween, an acetabularlandmark contacting device coupled with the distal end of the handlingdevice, and a surgical orientation device for detecting and recording anorientation of the acetabular landmark or the acetabular implant.

In accordance with another embodiment, an acetabular surface preparationapparatus can comprise a handling device comprising a proximal end witha handle, a distal end, and a rotatable shaft extending therebetween, asurface preparation device coupled with the distal end and adapted toremove bone from the acetabulum to create a surface suitable forreceiving an acetabular implant, a sleeve disposed around the rotatableshaft and adapted to remain stationary while the shaft is rotating, anda surgical orientation device coupled with the sleeve such that theorientation device can remain stationary while the rotatable shaft isrotated.

In accordance with another embodiment, an acetabular implant placementdevice can comprise a handling device comprising a proximal end with ahandle, a distal end, and an elongate member extending therebetween,wherein the distal end comprises an implant contacting structure adaptedto couple with an acetabular implant, and a surgical orientation devicecoupled with the handling device such that the orientation of at leastone of the handling device and the surgical orientation device can bemonitored as the acetabular implant is advanced into the acetabulum.

In accordance with another embodiment, a method for preparing apatient's hip for receiving an implant can comprise providing a firstorthopedic system comprising a reference post comprising an orientationsensor, an impactor coupled with the reference post, a first angleassessment guide, and a portable surgical orientation device attached tothe angle assessment guide, attaching the reference post to a hip boneof the patient, measuring and recording a reference distance from thereference post to an anatomical landmark using the portable surgicalorientation device, removing the angle assessment guide, impactor, andportable surgical orientation device from the reference post, providinga second orthopedic system comprising an alignment guide, a second angleassessment guide attached to the alignment guide, and the portablesurgical orientation device attached to the alignment guide, measuringan orientation of an anatomical plane using the second angle assessmentguide, orienting an implant relative to the anatomical plane andinserting the implant into the acetabulum using the second orthopedicsystem, attaching a femoral broach to the patient's femur, the femoralbroach including a head, positioning the head in the implant, providingthe first orthopedic system a second time, and measuring changes in thereference distance.

In accordance with another embodiment, a method for preparing apatient's hip for receiving an implant can comprise attaching a firstorthopedic system to the patient's hip with a reference device, thefirst orthopedic system comprising a portable surgical orientationdevice, measuring and recording a reference distance from the referencedevice to an anatomical landmark using the portable surgical orientationdevice, measuring an orientation of an anatomical plane on the patient'ship using a second orthopedic system, the second orthopedic systemcomprising the portable surgical orientation device, orienting animplant relative to the anatomical plane using the second orthopedicsystem, inserting the implant into the acetabulum, inserting aprosthetic femoral head into the implant, and measuring changes in thereference distance using the first orthopedic system.

In accordance with another embodiment, a method for positioning apatient in a hip procedure can comprise advancing a reference deviceinto a patient's pelvic bone, coupling a surgical orientation devicewith the reference device such that the orientation device is notmoveable relative to the pelvic bone, measuring at least one of theposition or orientation of at least a portion of the patient's hip jointusing the surgical orientation device, and moving the patient's hipjoint to selected position the patient relative to a fixed referenceframe based on the measurement on the surgical orientation device.

In accordance with another embodiment, a method for assessing relativeposition of portions of a hip joint can comprise coupling a surgicalorientation device to a first bone of a patient's hip at a firstlocation with a reference device, measuring a reference distance fromthe reference device to an anatomical landmark of a second bone usingthe surgical orientation device, performing a hip procedure, and afterperforming the hip procedure, confirming the position of the anatomicallandmark relative to the first location.

In accordance with another embodiment, a method of placing an acetabularimplant can comprise providing an orientation apparatus comprising anelongate member having a handle disposed at a proximal end, an angleassessment device disposed at a distal end, and a surgical orientationdevice, advancing the angle assessment device into contact with ananatomical landmark of the acetabulum while measuring orientation of thelandmark, preparing the acetabulum for receiving the acetabular implant,placing the acetabular implant within the acetabulum, and advancing theangle assessment device into contact with the acetabular implant toconfirm the orientation of the implant.

In accordance with another embodiment, a method of preparing anacetabular surface for receiving an acetabular implant can compriseproviding a handle, a shaft rotatably coupled with the handle, a reamercoupled a distal end of the shaft, and an orientation device coupled ina fixed position relative to the handle, providing contact between thereamer and an acetabular surface while rotating the shaft and reamer toremove bone within the acetabulum, and measuring the orientation of thereamer while providing contact between the reamer and an acetabularsurface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a representation of a human anatomy, identifying generallythe femur, pelvis, iliac spine, and lesser trochanter;

FIG. 2A is a side view of a orthopedic system according to oneembodiment for establishing a reference location on a patient's anatomy;

FIG. 2B is a front view of the orthopedic system of FIG. 2A;

FIG. 2C is a perspective view of the orthopedic system of FIG. 2A;

FIG. 2D is a front view of a reference post according to one embodiment;

FIG. 3A is a side view of an orthopedic system according to oneembodiment for measuring distances in and around a joint;

FIG. 3B is a top view of the orthopedic system of FIG. 3A;

FIG. 4 is an exploded perspective view of a orthopedic system accordingto one embodiment for determining an orientation of a plane in apatient's anatomy;

FIG. 5 is a perspective view of a orthopedic system according to oneembodiment for preparing a portion of a patient's anatomy to receive animplant;

FIG. 6 is a perspective view of a orthopedic system according to oneembodiment for orienting a prosthetic component;

FIG. 7 is a perspective view of a surgical orientation device accordingto one embodiment that can be used in conjunction with one or more ofthe orthopedic systems described herein;

FIG. 8 is a back view of the surgical orientation device of FIG. 7;

FIG. 9 is a perspective view of the surgical orientation device of FIG.7;

FIG. 10A is a top view of the surgical orientation device of FIG. 7;

FIG. 10B is a bottom view of the surgical orientation device of FIG. 7;

FIG. 11 is a block diagram of an electrical system of the surgicalorientation device of FIG. 7;

FIGS. 12A-C illustrate operation of accelerometers according toembodiments that can be used as sensors in the electrical system of FIG.11;

FIG. 12D is a perspective view of interior components of the surgicalorientation device of FIG. 7;

FIG. 12E is a flow chart of an embodiment of an orientation measurementprocess performed by the surgical orientation device of FIG. 7;

FIG. 13 illustrates a method in which the patient's hip is generallyparallel to an operating table and a reference post of the orthopedicsystem of FIGS. 2A-C is inserted into the patient's anatomy;

FIG. 13A illustrates a method in which the patient's hip is generallyparallel to an operating table and a fixture is provided for coupling areference post of the orthopedic system of FIGS. 2A-C with the patient'sanatomy;

FIG. 13B illustrates a technique for coupling a reference post with thefixture shown in FIG. 13A;

FIG. 14 illustrates a method in which the orthopedic system of FIGS.3A-B is being used to measure a distance between the fixed referencepost and a reference location on the patient's anatomy;

FIG. 14A illustrates a method in which the orthopedic system of FIGS.3A-B is used to measure a distance between the fixed reference post anda reference location on the patient's anatomy;

FIG. 15-18 illustrate techniques for resecting a femoral head andcleaning of osteophytes around the acetabular rim;

FIG. 19 is a perspective view of the orthopedic system of FIG. 4 beingused to determine the orientation of a plane defined by landmarks on thepatient's acetabular rim;

FIG. 20 is a perspective view of the orthopedic system of FIG. 5 beingused to ream out a portion or portions of the patient's acetabularsocket;

FIGS. 21 and 22 are perspective views of the orthopedic system of FIG. 6being used to orient a prosthetic acetabular cup;

FIG. 23 is a perspective view of a polymer insert being placed in theprosthetic acetabular cup;

FIGS. 24-26 are perspective views of a preparation of femoral canal,broach, and prosthetic femoral head;

FIG. 27 is a perspective view of the patient's hip joint being reducedback into place, with the prosthetic femoral head inserted into theprosthetic acetabular cup;

FIG. 28 is a perspective view of the orthopedic system of FIGS. 3A-Bbeing used again to measure a distance between the fixed reference postand a reference location on the patient's anatomy; and

FIGS. 29A and B are schematic illustrations of a change in leg length(LL) and leg offset (OS) as measured prior to and after a hippreparation procedure according to one embodiment.

FIGS. 30A-W show various embodiments of user interface screens that canbe displayed during an orthopedic procedure or procedures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Although certain preferred embodiments and examples are disclosed below,it will be understood by those skilled in the art that the inventivesubject matter extends beyond the specifically disclosed embodiments toother alternative embodiments and/or uses of the inventions, and toobvious modifications and equivalents thereof. Thus it is intended thatthe scope of the inventions herein disclosed should not be limited bythe particular disclosed embodiments described below. Thus, for example,in any method or process disclosed herein, the acts or operations makingup the method/process may be performed in any suitable sequence, and arenot necessarily limited to any particular disclosed sequence. Forpurposes of contrasting various embodiments with the prior art, certainaspects and advantages of these embodiments are described whereappropriate herein. Of course, it is to be understood that notnecessarily all such aspects or advantages may be achieved in accordancewith any particular embodiment. Thus, for example, it should berecognized that the various embodiments may be carried out in a mannerthat achieves or optimizes one advantage or group of advantages astaught herein without necessarily achieving other aspects or advantagesas may be taught or suggested herein.

I. Overview of Systems and Methods

The following sections describe in detail systems and methods for a hipreplacement procedure. The orthopedic systems described herein includeorthopedic systems and orthopedic devices for preparing the hip toreceive prosthetic components. The systems include but are not limitedto orthopedic systems 10, 110, 210, 310, and 410 described herein, eachof which can be used during various stages of an orthopedic procedure orprocedures, such as for example a total hip replacement procedure. Theseorthopedic systems and devices can be used to perform minimallyinvasive, cost-efficient, successful orthopedic procedures.

II. Orthopedic Systems

A number of different orthopedic systems are discussed below. Thesesystems are useful, for example, for modifying the natural hip joint toenable the hip joint to have a prosthetic component or components, suchcomponents including but not limited to a prosthetic acetabular cup.

FIG. 1 illustrates a pelvis, femur, iliac spine, and lesser and greatertrochanter regions. As will be described further herein, these and/orother anatomical locations and landmarks can be referenced and usedthroughout an orthopedic procedure or procedures in conjunction with thesystems described herein.

A. Orthopedic System for Establishing a Reference Location on thePatient's Anatomy

With reference to FIGS. 2A-D, an orthopedic system 10 can be used toprovide a fixed reference on a patient's anatomy, as well as to providean anchor and/or support for other orthopedic systems. As illustrated inFIG. 2A, the orthopedic system 10 can comprise a surgical orientationdevice 12, reference device 14, impactor 16, and angle assessment guide18.

1. Device for Use as a Reference in the Patient's Anatomy

The system 10 can comprise a device or component that serves as areference for other systems or devices. For example, and as illustratedin FIG. 2A, the reference device 14 can comprise a reference post 14,and can serve as a reference for other systems or devices. The referencepost 14 can comprise a thin, metallic pin that can be at least partiallydriven (e.g. hammered with a slap hammer) into a bony area on thepatient's anatomy. As will be described further herein, the referencepost 14 can be partially driven, for example, into the iliac spine on apatient's pelvis. Other types of reference posts can also be used. Thereference post 14 can also be used to hold back tissue that wouldotherwise cover the surgical field, e.g., skin and muscle and othersub-dermal tissues. In a preferred arrangement, the reference post 14also can serve as an anchor or otherwise mechanically support otherjoint preparation systems, as discussed below. The reference post 14 cancomprise a mounting structure. For example, the reference post 14 cansupport the system 310 in one technique. The reference post 14 also canbe coupled with an orientation sensor or sensors 15, which can bedisposed on the reference post's surface or inside the reference post14. The sensor or sensors 15 can detect orientation (e.g. position)and/or relative movement of the reference post 14. By detecting movementof the sensor(s) 15, movement of anatomy with which the reference postis coupled (e.g. surrounding bony area) can also be detected.

In one technique, the impactor 16 is used to assist in placement of thereference post 14. With continued reference to FIGS. 2A-C, the impactor16 can be releasably coupled to the reference post 14. The impactor 16can drive the reference post 14 into a bony area on the patient'sanatomy, and the impactor 16 can then be removed. The impactor 16 caninclude, for example, an elongate rod 20 with one end 22 for pounding orstriking with a hammer, and an opposite end 24 for releasably connectingto the impactor 14.

FIG. 2D shows another embodiment of a reference post 14′ which can beused with system 10. The reference post 14′ can comprise a proximalportion 30, an elongate body 32, and a distal portion 34. The proximalportion 30 can comprise a coupling structure comprising an annularrecess 36 defined between a proximally facing shoulder 38 and a distallyfacing shoulder 40. Other coupling structures are also possible. Asdescribed above, the impactor 16 can comprise a coupling structure 24for releasable attachment to the reference post 14′. In someembodiments, the end 24 of impactor 16 can comprise be fork-shaped asshown in FIG. 2C, and adapted to be received within the annular recess36 of the reference post 14. The fork-shaped structure 24 can abut atleast one of the proximal end 30 of the reference post 14 and theproximally facing shoulder 38 to transfer a force to the body 32 of thereference post 14 and drive distal end 34 into the bone. Thus, theimpactor 16 can enable the force of blows of the hammer to betransferred to the reference post 14 such that the distal end 34 ofreference post 14 can be advanced into the bone.

2. Device for Angle Assessment Relative to Operating Table

The system 10 can further comprise a device which can be used to orientthe patient's pelvis relative to the operating table. For example, andas described further herein, the angle assessment guide 18 can be usedto orient the patient's pelvis. The angle assessment guide 18 cancomprise a member 19, an attachment structures 26, and an end member 28.The attachment structure 26 can couple (e.g. attach, releasably attach)the angle assessment guide 18 to the impactor 16 and/or reference post14 at a certain angle “a”. The angle “a” can be any of a number ofangles, and preferably 45 degrees. FIG. 2A shows “a” at an angle ofapproximately 45 degrees. The angle assessment guide 18 can comprise anyof a number of sizes and shapes. For example, the angle assessment guidecan comprise a first elongate member, a second elongate member, and athird elongate member. The first elongate member can couple with theproximate end of the reference post 14, 14′, and can comprise theelongate rod 20 of the impactor. The second elongate member can couplewith the first elongate member at an angle relative to the firstelongate member (e.g. an acute angle), and can comprise member 19. Thethird elongate member can be mounted to the second elongate member, andcan comprise the cross-bar-shaped member 28 as illustrated in FIG. 2A.The surgical orientation device 12 can be releasably coupled to theangle assessment guide 18, such that movement of the angle assessmentguide 18 causes identical movement of the surgical orientation device12. The surgical orientation device can alternatively or additionally bereleasably coupled to the reference post 14. In some embodiments, thesurgical orientation device can be coupled to the cross-bar member 28with a coupling device such as that disclosed in U.S. patent applicationSer. No. 12/509,388, filed Jul. 24, 2009, the contents of which areincorporated in their entirety by reference herein.

3. Surgical Orientation Device

With continued reference to FIGS. 2A-C, the surgical orientation device12 can be can be used for verifying an alignment and/or measuringdistances. “Surgical orientation device” is a broad term as used herein,and includes, without limitation, devices which can be used alone or inconjunction with an orthopedic device or devices to identify or track arelative position of one or more orthopedic devices or anatomicalstructures, and can encompass any of the embodiments shown in thedrawings and as described herein, as well as any of the embodimentsshown or described in U.S. patent application Ser. No. 12/509,388, filedJul. 24, 2009, the contents of which are incorporated in their entiretyby reference herein.

For example, FIG. 7 shows an embodiment of a surgical orientation device12. The surgical orientation device 12 can comprise a compact device foruse in orienting a cutting guide or other surgical tool in a jointreplacement procedure. In some techniques, the surgical orientationdevice 12 can be configured for being hand-held during a procedure.Preferably the surgical orientation device 12 is portable.

The surgical orientation device 12 can be used, for example, to identifyan orientation of an anatomical plane, such as for example a planedefined by landmarks on a patient's acetabular rim. The surgicalorientation device 12 can be used, for example, to measure distances,such as for example a distance between the reference post 14 and ananatomical landmark or landmarks on the patient's anatomy. Other usesare also possible. Furthermore, the surgical orientation device 12, asdescribed herein, can be used alone or in conjunction with otherdevices, components, and/or systems, including but not limited to thesensor(s) 15 on the reference post 14, if included.

In a preferred arrangement, the surgical orientation device 12 cancomprise a generally rectangular-shaped structure having an outerhousing 30. The outer housing 30, as well as its contents can beportable. The outer housing 30 can be comprised, at least in part, ofplastic including but not limited to ABS, polycarbonate, or othersuitable material. The surgical orientation device 12 can be configuredfor hand-held use. The surgical orientation device 12 can be configuredfor mounting to other surgical devices, as discussed below.

With continued reference to FIG. 7, a front side 32, or a portion of thefront side 32, of the surgical orientation device 12 can comprise adisplay 34. The display 34 can be a separate component from the outerhousing 30 or can be integrated on or within the outer housing 30. Thedisplay 34 can comprise an output device. For example, the display 34can comprise a liquid crystal display (“LCD”) or Ferroelectric LiquidCrystal on Silicon (“FLCOS”) display screen. The display screen can besized such that a user can readily read numbers, lettering, and/orsymbols displayed on the display screen while performing a medicalprocedure. In an embodiment, the display 34 comprises a Quarter VideoGraphics Array (“QVGA”) Thin Film Transistor (“TFT”) LCD screen. Othertypes of display screens can also be used, as can other shapes, sizes,and locations for the display 24 on the surgical orientation device 12.

The surgical orientation device 12 can further comprise at least oneuser input device 36. The at least one user input device 36 can comprisea plurality of buttons located adjacent the display 34. The buttons canbe activated, for example, by a finger, hand, and/or instrument toselect a mode or modes of operation of the device 12, as discussedfurther below. In a preferred arrangement, the at least one user inputcomprises three buttons located underneath the display 34 as illustratedin FIG. 7. In other embodiments, the user input device 36 is a separatecomponent from the housing 30. For example, the user input device 36 cancomprise a remote input device coupled to the surgical orientationdevice 12 via a wired or wireless connection. In yet other embodiments,the user input device 36 comprises a microphone operating in conjunctionwith a speech recognition module configured to receive and processverbal instructions received from a user.

As discussed below, the surgical orientation device 12 can include auser interface with which a clinician can interact during a procedure.In one embodiment, the display 34 and at least one user input 36 canform a user interface. The user interface can allow a surgeon, medicalpersonnel, and/or other user to operate the surgical orientation device12 with ease, efficiency, and accuracy. Specific examples andillustrations of how the user interface can operate in conjunction withspecific methods are disclosed further herein.

FIGS. 8 and 9 show a back side 37 of the surgical orientation device 12.The back side 37 can include an attachment structure or structures 38,as well as a gripping feature or features 39 for facilitating handlingof the surgical orientation device 12. The attachment structures 38 canfacilitate attachment of the surgical orientation device 12 to anotherdevice, such as for example a coupling device (not shown). In apreferred arrangement, the attachment structures 38 comprise grooves, orchannels 40, along a portion of the back side of the surgicalorientation device 12.

The attachment structures 38 can be formed, for example, from protrudingportions of the back side of the surgical orientation device 12, and canextend partially, or entirely, along the back side of the surgicalorientation device 12. The attachment structures 38 can receivecorresponding, or mating, structures from the coupling device 14, so asto couple, or lock, the coupling device to the surgical orientationdevice 12. FIGS. 10A and 10B show top and bottom sides 41 a, 41 b of thesurgical orientation device 12. The surgical orientation device 12 cancomprise optical components 42 that can be located on the top side 41 a,the bottom side 41 b, or the top and bottom sides 41 a, 41 b of thesurgical orientation device 12. The optical components 42 can comprisetransparent windows 44 integrated into the surgical orientation device12. The optical components 42 can be windows that permit visible light(e.g. laser light) to emit from the top side 31 a, the bottom side 31 b,or both the top and bottom sides 41 a, 41 b of the surgical orientationdevice 12. While the embodiment illustrated in FIGS. 10 a and 10 b showstwo windows 44 for transmitting light, other numbers are also possible.Additionally, while the optical components 42 are shown located on thetop and bottom of the surgical orientation device 12, in otherembodiments the optical components 42 can be located in other positionsand/or on other portions of the surgical orientation device 12.

FIG. 11 illustrates a high-level block diagram of an electrical system1100 of the surgical orientation device 12. The electrical system 1100comprises an electronic control unit 1102 that communicates with one ormore sensor(s) 1104, one or more visible alignment indicators 1106, apower supply 1108, a display 1110, external memory 1112, one or moreuser input devices 1114, other output devices 1116 and/or one or moreinput/output (“I/O”) ports 1118.

In general, the electronic control unit 1102 can receive input from thesensor(s), the external memory 1112, the user input devices 1114 and/orthe I/O ports 1118 and controls and/or transmits output to the visiblealignment indicators 1106, the display 1110, the external memory 1112,the other output devices 1116 and/or the I/O ports 1118. The electroniccontrol unit 1102 can be configured to receive and send electronic data,as well as perform calculations based on received electronic data. Incertain embodiments, the electronic control unit 1102 can be configuredto convert the electronic data from a machine-readable format to a humanreadable format for presentation on the display 1110. The electroniccontrol unit 1102 can comprise, by way of example, one or moreprocessors, program logic, or other substrate configurationsrepresenting data and instructions, which can operate as describedherein. In other embodiments, the electronic control unit 1102 cancomprise controller circuitry, processor circuitry, processors, generalpurpose single-chip or multi-chip microprocessors, digital signalprocessors, embedded microprocessors, microcontrollers and/or the like.The electronic control unit 1102 can have conventional address lines,conventional data lines, and one or more conventional control lines. Inyet other embodiments, the electronic control unit 1102 can comprise anapplication-specific integrated circuit (ASIC) or one or more modulesconfigured to execute on one or more processors. In certain embodiments,the electronic control unit 1102 can comprise an AT91SAM7SEmicrocontroller available from Atmel Corporation.

The electronic control unit 1102 can communicate with internal memoryand/or the external memory 1112 to retrieve and/or store data and/orprogram instructions for software and/or hardware. The internal memoryand the external memory 1112 can include random access memory (“RAM”),such as static RAM, for temporary storage of information and/or readonly memory (“ROM”), such as flash memory, for more permanent storage ofinformation. In some embodiments, the external memory 1112 includes anAT49BV160D-70TU Flash device available from Atmel Corporation and aCY62136EV30LL-45ZSXI SRAM device available from Cypress SemiconductorCorporation. The electronic control unit 1102 can communicate with theexternal memory 1112 via an external memory bus.

In general, the sensor(s) 1104 can be configured to provide continuousreal-time data to the surgical orientation device 12. The electroniccontrol unit 1102 can be configured to receive the real-time data fromthe sensor(s) 1104 and to use the sensor data to determine, estimate,and/or calculate an orientation (e.g. position) of the surgicalorientation device 12. The orientation information can be used toprovide feedback to a user during the performance of a surgicalprocedure, such as a total hip replacement surgery, as described in moredetail herein.

In some arrangements, the one or more sensors 1104 can comprise at leastone orientation sensor configured to provide real-time data to theelectronic control unit 1102 related to the motion, orientation (e.g.position) of the surgical orientation device 12. For example, a sensormodule 1104 can comprise at least one gyroscopic sensor, accelerometersensor, tilt sensor, magnetometer and/or other similar device or devicesconfigured to measure, and/or facilitate determination of, anorientation of the surgical orientation device 12. The term “module” asused herein can include, but is not limited to, software or hardwarecomponents which perform certain tasks. Thus, a module can includeobject-oriented software components, class components, procedures,subroutines, data structures, segments of program code, drivers,firmware, microcode, circuitry, data, tables, arrays, etc. Those withordinary skill in the art will also recognize that a module can beimplemented using a wide variety of different software and hardwaretechniques.

In some embodiments, the sensors 1104 can be configured to providemeasurements relative to a reference point(s), line(s), plane(s), and/orgravitational zero. Gravitational zero, as referred to herein, refersgenerally to an orientation in which an axis of the sensor 1104 isperpendicular to the force of gravity, and thereby experiences noangular offset, for example tilt, pitch, roll, or yaw, relative to agravitational force vector. In other embodiments, the sensor(s) 1104 canbe configured to provide measurements for use in dead reckoning orinertial navigation systems.

In various embodiments, the sensor(s) 1104 comprise one or moreaccelerometers that measure the orientation of the surgical orientationdevice 12 relative to gravity. For example, the accelerometers can beused as tilt sensors to detect rotation of the surgical orientationdevice 12 about one or more of its axes. For example, the one or moreaccelerometers can comprise a dual axis accelerometer (which can measurerotation about two axes of rotation). The changes in orientation aboutthe axes of the accelerometers can be determined relative togravitational zero and/or to a reference plane registered during atibial or femoral preparation procedure as described herein.

In certain embodiments, a multi-axis accelerometer (such as theADXL203CE MEMS accelerometer available from Analog Devices, Inc. or theLIS331DLH accelerometer available from ST Microelectronics) detectschanges in orientation about two axes of rotation. For example, themulti-axis accelerometer can detect changes in angular position from ahorizontal plane (e.g., anterior/posterior rotation) of the surgicalorientation device 12 and changes in angular position from a verticalplane (e.g., roll rotation) of the surgical orientation device 12. Thechanges in angular position from the horizontal and vertical planes ofthe surgical orientation device 12 as measured by the sensor 1104 can beused to determine changes in orientation of the surgical orientationdevice 12.

In some arrangements, the sensors 1104 can comprise at least one single-or multi-axis gyroscope sensor and at least one single- or multi-axisaccelerometer sensor. For example, a sensor module 1104 can comprise athree-axis gyroscope sensor (or three gyroscope sensors) and athree-axis accelerometer (or three accelerometer sensors) to provideorientational measurements for all six degrees of freedom of thesurgical orientation device 12. In some embodiments, the sensors providean inertial navigation or dead reckoning system to continuouslycalculate the orientation and velocity of the surgical orientationdevice 12 without the need for external references

In some embodiments, the sensors 1104 comprise one or moreaccelerometers and at least one magnetometer. The magnetometer can beconfigured to measure a strength and/or direction of one or moremagnetic fields in the vicinity of the surgical orientation device 12.The magnetometer can advantageously be configured to detect changes inangular position about a vertical axis. In other embodiments, thesensors 1104 comprise one or more sensors capable of determiningdistance measurements. For example a sensor located in the surgicalorientation device 12 can be in electrical communication (wired orwireless) with an emitter element mounted at the end of a measurementprobe. For example, sensor 15 in reference post 14 can comprise anemitter element. In certain embodiments, the electrical control unit canbe configured to determine the distance between the sensor and emitter(for example, an axial length of a measurement probe corresponding to adistance to an anatomical landmark, such as a bony eminence of thepelvis or femur, such as the greater or lesser trochanter).

In other embodiments, the one or more sensors 1104 can comprise atemperature sensor to monitor system temperature of the electricalsystem 1100. Operation of some of the electrical components can beaffected by changes in temperature. The temperature sensor can beconfigured to transmit signals to the electronic control unit 1102 totake appropriate action. In addition, monitoring the system temperaturecan be used to prevent overheating. In some embodiments, the temperaturesensor comprises a NCP21WV103J03RA thermistor available from MurataManufacturing Co. The electrical system 1100 can further includetemperature, ultrasonic and/or pressure sensors for measuring propertiesof biological tissue and other materials used in the practice ofmedicine or surgery, including determining the hardness, rigidity,and/or density of materials, and/or determining the flow and/orviscosity of substances in the materials, and/or determining thetemperature of tissues or substances within materials.

In certain embodiments, the sensors 1104 can facilitate determination ofan orientation of the surgical orientation device 12 relative to areference orientation established during a preparation and alignmentprocedure performed during orthopedic surgery. Further details regardingthe operation of the sensors in conjunction with a total hip replacementsurgery are described herein.

The one or more sensors 1104 can form a component of a sensor modulethat comprises at least one sensor, signal conditioning circuitry, andan analog-to-digital converter (“ADC”). In certain embodiments, thecomponents of the sensor module 1104 are mounted on a stand-alonecircuit board that is physically separate from, but in electricalcommunication with, the circuit board(s) containing the other electricalcomponents described herein. In other embodiments, the sensor module isphysically integrated on the circuit board(s) with the other electricalcomponents. The signal conditioning circuitry of the sensor module cancomprise one or more circuit components configured to condition, ormanipulate, the output signals from the sensor(s) 1104. In certainembodiments, the signal conditioning circuitry comprises filteringcircuitry and gain circuitry. The filtering circuitry can comprise onemore filters, such as a low pass filter. For example, a 10 Hz singlepole low pass filter can be used to remove vibrational noise or otherlow frequency components of the sensor output signals. The gaincircuitry can comprise one or more operational amplifier circuits thatcan be used to amplify the sensor output signals to increase theresolution potential of the sensor. For example, the operationalamplifier circuit can provide gain such that a 0 g output results in amidrange (e.g., 1.65 V signal), a +1 g output results in a full scale(e.g., 3.3 V) signal and a −1 g output results in a minimum (0 V) signalto the ADC input.

In general, the ADC of the sensor module can be configured to convertthe analog output voltage signals of the sensor(s) 1104 to digital datasamples. In certain embodiments, the digital data samples comprisevoltage counts. The ADC can be mounted in close proximity to the sensorto enhance signal to noise performance. In certain embodiments, the ADCcomprises an AD7921 two channel, 12-bit, 250 Kiloseconds per Sample ADC.In an arrangement having a 12-bit ADC can generate 4096 voltage counts.The ADC can be configured to interface with the electronic control unit1102 via a serial peripheral interface port of the electronic controlunit 1102. In other embodiments, the electronic control unit 1102 cancomprise an on-board ADC that can be used to convert the sensor outputsignals into digital data counts.

With continued reference to FIG. 11, the visible alignment indicators1106 can comprise one or more lasers, which can be configured to projectlaser light through the optical component or components 32 describedabove. For example, the visible alignment indicators 1106 can comprise aforward laser and an aft laser. The laser light can be used to project apoint, a plane, and or a cross-hair onto a target or targets, includingbut not limited to an anatomical feature or landmark, to providealternative or additional orientation information to a surgeon regardingthe orientation of the orientation device 12. For example, laser lightcan be used to project a plane on a portion of bone to indicate aresection line and a cross-hair laser pattern can be used to ensurealignment along two perpendicular axes. In certain embodiments, thelaser light or other type of probe (e.g. a mechanical probe such as anelongate rod) can be used to mark or identify landmarks on the patient'ship area, such as the lesser trochanter and/or iliac spine. In certainembodiments, the laser light or other type of probe can be used toconstrain a degree of freedom, such as rotation about a vertical axis,of an instrument relative to anatomy or one instrument relative toanother. The probe can be used, for example, to return an instrument toa specific rotational orientation. In certain embodiments, the visiblealignment indicators 1106 can be used to determine a distance to ananatomical feature or landmark (for example, a laser distancemeasurement system). For example, the electronic control unit 1102 canproject laser light to a target and a sensor 1104 within the surgicalorientation device can sense the laser light reflected back from thetarget and communicate the information to the electronic control unit.The electronic control unit 1102 can then be configured to determine thedistance to the target. The lasers can be controlled by the electroniccontrol unit 1102 via pulse width modulation (“PWM”) outputs. In certainembodiments, the visible alignment indicators 1106 comprise Class 2Mlasers. In other embodiments, the visible alignment indicators 1106comprises other types of lasers or light sources.

The power supply 1108 can comprise one or more power sources configuredto supply DC power to the electronic system 1100 of the surgicalorientation device 12. In certain embodiments, the power supply 1108comprises one or more rechargeable or replaceable batteries and/or oneor more capacitive storage devices (for example, one or more capacitorsor ultracapacitors). In other embodiments, power can be supplied byother wired and/or wireless power sources. In preferred arrangements,the power supply 1108 comprises two AA alkaline, lithium, orrechargeable NiMH batteries. The surgical orientation device 12 can alsoinclude a DC/DC converter to boost the DC power from the power supply toa fixed, constant DC voltage output (e.g., 3.3 volts) to the electroniccontrol unit 1102. In some embodiments, the DC/DC converter comprises aTPS61201DRC synchronous boost converter available from TexasInstruments. The electronic control unit 1106 can be configured tomonitor the battery level if a battery is used for the power supply1108. Monitoring the battery level can advantageously provide advancenotice of power loss. In certain embodiments, the surgical orientationdevice 12 can comprise a timer configured to cause the surgicalorientation device 12 to temporarily power off after a predeterminedperiod of inactivity and/or to permanently power off after apredetermined time-out period.

As discussed above, the display 1110 can comprise an LCD or other typescreen display. The electronic control unit 1102 communicates with thedisplay via the external memory bus. In certain embodiments, theelectronic system 1100 comprises a display controller and/or an LEDdriver and one or more LEDs to provide backlighting for the display1110. For example, the display controller can comprise an LCD controllerintegrated circuit (“IC”) and the LED driver can comprise a FAN5613 LEDdriver available from Fairchild Semiconductor International, Inc. Theelectronic control unit 1102 can be configured to control the LED drivervia a pulse width modulation port to control the brightness of the LEDdisplay. For example, the LED driver can drive four LEDs spaced aroundthe display screen to provide adequate backlighting to enhancevisibility. The display can be configured to display one or moreon-screen graphics. The on-screen graphics can comprise graphical userinterface (“GUI”) images or icons. The GUI images can includeinstructive images, such as illustrated surgical procedure steps, orvisual indicators of the orientation information received from thesensor(s) 1104. For example, the display can be configured to displaydegrees and either a positive or negative sign to indicate direction ofrotation from a reference plane and/or a bubble level indicator to aid auser in maintaining a particular orientation. The display can also beconfigured to display alphanumeric text, symbols, and/or arrows. Forexample, the display can indicate whether a laser is on or off and/orinclude an arrow to a user input button with instructions related to theresult of pressing a particular button.

With continued reference to FIG. 11, the user input device(s) 1114 cancomprise buttons, switches, a touchscreen display, a keyboard, ajoystick, a scroll wheel, a trackball, a remote control, a microphone,and the like. The user input devices 1114 can allow the user to enterdata, make selections, input instructions or commands to the surgicalorientation device 12, verify a position of the surgical orientationdevice 12, turn the visible alignment indicators 1106 on and off, and/orturn the entire surgical orientation device 12 on and off. The otheruser output devices 1116 (i.e. other than the display 1110) can comprisean audio output, such as a speaker, a buzzer, an alarm, or the like. Forexample, the audio output can provide a warning to the user when aparticular condition occurs. The output devices 1116 can also comprise avisible output, such as one or more LED status or notification lights(for example, to indicate low battery level, an error condition, etc.).The audio output can comprise different patterns, tones, cadences,durations, and/or frequencies to signify different conditions or events.In other embodiments, output from the electronic control unit 1102 canbe sent to external display devices, data storage devices, servers,and/or other computing devices (e.g., via a wireless networkcommunication link).

The I/O ports 1118 of the electronic control unit 1102 can comprise aJTAG port and one or more serial communication ports. The JTAG port canbe used to debug software installed on the electronic control unit 1102during testing and manufacturing phases. The JTAG port can be configuredsuch that it is not externally accessible post-manufacture. The serialcommunication ports can include a Universal Serial Bus (“USB”) portand/or one or more universal asynchronous receiver/transmitters (“UART”)ports. At least one of the UART ports can be accessible externallypost-manufacture. The external UART port can be an infrared (“IR”)serial port in communication with an infrared (“IR”) transceiver. The IRserial port can be used to update the software installed on theelectronic control unit 1102 post-manufacture and/or to test theoperation of the electronic control unit 1102 by outputting data fromthe electronic control unit 1102 to an external computing device via anexternal wireless connection. Other types of I/O ports are alsopossible.

As described above, the sensor(s) 1104 can comprise one or moreaccelerometers. Accelerometers can measure the static acceleration ofgravity in one or more axes to measure changes in tilt orientation. Forexample, a three-axis accelerometer can measure the static accelerationdue to gravity along three orthogonal axes, as illustrated in FIG. 12A.A two-axis accelerometer can measure the static acceleration due togravity along two orthogonal axes (for example, the x and y axes of FIG.12A). The output signals of an accelerometer can comprise analog voltagesignals. The output voltage signals for each axis can fluctuate based onthe fluctuation in static acceleration as the accelerometer changes itsorientation with respect to the gravitational force vector. In certainembodiments, an accelerometer experiences static acceleration in therange from −1 g to +1 g through 180 degrees of tilt (with −1 gcorresponding to a −90 degree tilt, 0 g corresponding to a zero degreetilt, and +1 g corresponding to a +90 degree tilt. The accelerationalong each axis can be independent of the acceleration along the otheraxis or axes.

FIG. 12B illustrates a measured acceleration along each of the threeaxes of a three-axis accelerometer in six different orientationpositions. TOP and BOTTOM labels, as well as a circle indicating Pin 1of the accelerometer, have been included to aid in determining thevarious orientations. A gravitational force reference vector isillustrated as pointing straight down toward the Earth's surface. Atpositions A and B, the x-axis and the y-axis of the accelerometer areperpendicular to the force of gravity and the z-axis of theaccelerometer is parallel to the force of gravity; therefore, the x andy acceleration components of static acceleration due to gravity atpositions A and B are 0 g and the z component of static acceleration dueto gravity at positions A and B is +1 g and −1 g, respectively. Atpositions C and E, the x-axis and the z-axis of the accelerometer areperpendicular to the force of gravity and the y-axis is parallel to theforce of gravity; therefore, the x and z acceleration components ofstatic acceleration due to gravity at positions C and E are 0 g and they component of static acceleration due to gravity at positions C and Eis +1 g and −1 g, respectively. At positions D and F, the y-axis andz-axis are perpendicular to the force of gravity and the x-axis isparallel to the force of gravity; therefore, the y and z accelerationcomponents of static acceleration due to gravity at positions D and Fare 0 g and the x component of static acceleration due to gravity atpositions D and F is +1 g and −1 g, respectively. A dual-axisaccelerometer operates in the same manner but without the z component.In certain arrangements, a three-axis accelerometer can be used as atiltmeter to measure changes in orientation about two axes.

Multi-axis accelerometers can be conceptualized as having a separateaccelerometer sensor for each of its axes of measurement, with eachsensor responding to changes in static acceleration in one plane. Incertain embodiments, each accelerometer sensor is most responsive tochanges in tilt (i.e., operates with maximum or optimum accuracy and/orresolution) when its sensitive axis is substantially perpendicular tothe force of gravity (i.e., when the longitudinal plane of theaccelerometer sensor is parallel to the force of gravity) and leastresponsive when the sensitive axis is parallel to the force of gravity(i.e., when the longitudinal plane of the accelerometer sensor isperpendicular to the force of gravity). FIG. 12C illustrates the outputof the accelerometer in g's as it tilts from −90 degrees to +90 degrees.As shown, the tilt sensitivity diminishes between −90 degrees and −45degrees and between +45 degrees and +90 degrees (as shown by thedecrease in slope). This resolution problem at the outer ranges of tiltmotion makes the measurements much less accurate for tilt measurementsover 45 degrees. In certain embodiments, when the mounting angle of thesurgical orientation device 12 is known, the sensor(s) 1104 can bemounted to be offset at an angle such that the accelerometer sensors canoperate in their more accurate, steeper slope regions. For example, foruse during the knee surgery preparation procedures described herein, thesensor(s) 1104 can be mounted at approximately a 22-degree anglerelative to the anterior-posterior axis of the surgical orientationdevice 12 to account for a predetermined range of motion of the surgicalorientation device 12 about the flexion/extension axis during theprocedures. It should be appreciated by one of ordinary skill in the artthat the accelerometer can be mounted at acute angles other thanapproximately 22 degrees. In other arrangements, the sensor(s) 1104 canbe mounted to be offset to account for a predetermined range of motionabout other axes of rotation as well. In yet other arrangements, forexample, when a three-axis accelerometer is used, the accelerometersensor(s) can be mounted in parallel with the anterior-posterior axis ofthe surgical orientation device 12. In one three-axis accelerometerarrangement, a handoff system can be incorporated to ensure that theaccelerometer sensors with the most accurate reading (e.g., <45 degrees)are being used at each orientation position. The handoff system canemploy hysteresis to avoid “bouncing” phenomena during the handoffsbetween the accelerometer sensors.

FIG. 12D illustrates the inside of the surgical orientation device 12according to at least one embodiment. The surgical orientation device 12can comprise one or more circuit boards and/or other circuitry capableof installation within the surgical orientation device 12. Asillustrated, the surgical orientation device 12 can comprise a sensorboard 46A and a main board 46B. The components of the sensor module(including the sensor(s) 1104) can be mounted on the sensor board 46Aand the other components of the electrical system 1100 are mounted onthe main board 46B. The sensor board 46A can comprise one or moresensors 50 (e.g., sensor(s) 1104 as described above). In alternativeembodiments, the sensor board 46A and the main board 46B can be combinedinto a single circuit board. The sensor board 46A and the main board 46Bcan comprise rigid or flexible circuit boards. The sensor board 46A andthe main board 46B can be fixedly or removably coupled to the outerhousing 20.

As illustrated, the sensor board 46A is mounted at an approximately22-degree angle relative to a plane extending longitudinally through thehousing 30, which can be parallel to or correspond to ananterior-posterior axis of the main board 46B. As described above,mounting the sensor board 46A at an offset angle can enable the one ormore sensors to operate in the regions of maximum or optimumsensitivity, accuracy and/or resolution. The particular mounting offsetangle can be selected based on a range of motion of the surgicalorientation device 12 during a particular orthopedic procedure. As shownin FIG. 12D, the surgical orientation device 12 can include two AAbatteries 38 as the power supply 1110 for providing power to thesurgical orientation device 12. The surgical orientation device 12 alsocan include lasers 42 as the visible alignment indicators 1106 describedabove.

FIG. 12E is a high-level flowchart of an exemplary conversion processfor converting an analog voltage output signal of a multi-axisaccelerometer into an angle degree measurement for presentation on thedisplay 34. Although the steps are described as being implemented withhardware and/or software, each of the steps illustrated in FIG. 12E canbe implemented using hardware and/or software. It should be appreciatedthat a similar conversion process can be performed for any other type ofsensor or for multiple separate sensors without departing from thespirit and/or scope of the disclosure.

For each axis of rotation measured (e.g., pitch and roll), themulti-axis accelerometer can continuously output an analog voltagesignal. At Block 1205, the signal conditioning circuitry of the sensormodule can filter the analog output voltage signal (e.g., with a lowpass filter) to remove noise from the signal that may be present due tothe high sensitivity of the multi-axis accelerometer. At Block 1210, thesignal conditioning circuitry amplifies, or boosts, the output voltagesignal, for example, via the gain circuitry described above.

At Block 1215, the ADC can convert the continuous analog voltage signalinto a discrete digital sequence of data samples, or voltage counts. Incertain embodiments, the ADC can sample the analog voltage signal onceevery two milliseconds; however, other sampling rates are possible. Incertain embodiments, the analog voltage signal is oversampled. At Block1220, the electronic control unit 1102 can generate a stable data pointto be converted to an angle measurement. The electronic control unit1102 can apply a median filter to the sampled data to eliminate outliers(e.g., spikes) in the data. For example, the electronic unit 1102 canuse an 11-sample median filter to generate the middle value from thelast 11 samples taken. The output of the median filter can then be fedinto a rolling average filter (for example, a 128 sample rolling averagefilter). The rolling average filter can be used to smoothe or stabilizethe data that is actually converted to an angle measurement. Theelectronic control unit 1102 can implement Blocks 1215 and 1220 using afinite impulse response (“FIR”) or an infinite impulse response (“IIR”)filter implemented in a software module.

At Block 1225, the electronic control unit 1102 can convert the voltagecount data to an angle measurement in degrees. In performing theconversion, the electronic control unit 1102 can be configured to applya calibration conversion algorithm based on a calibration routineperformed during a testing phase prior to sale of the surgicalorientation device 12. The calibration conversion can be configured toaccount for unit-to-unit variations in components and sensor placement.The calibration routine can be performed for each axis being monitoredby the multi-axis accelerometer. The calibration conversion can compriseremoving any mechanical or electrical offsets and applying anappropriate gain calibration for a positive or negative tilt.

As described above, the ADC can comprise an ADC with 12-bit resolution,which provides 4096 distinct voltage counts, wherein a −90 degree tiltcorresponds to 0 counts (−2048 signed counts), a zero degree tiltcorresponds to 2048 counts (0 signed counts), and a +90 degree tiltcorresponds to 4096 counts (+2048 signed counts). The tilt angle foreach axis (e.g., pitch and roll) of the multi-axis accelerometer can becalculated from the voltage count data based on standard trigonometricrelationships as the arcsin of the acceleration component in eachparticular axis. In arrangements in which the electronic control unit1102 applies the calibration conversion, the tilt angle for each axiscan be calculated as follows:

$\begin{matrix}{{{ANGLE} = {a\; {\sin \left\lbrack \frac{\left. {\left( {{{SignedADC}\mspace{14mu} {Counts}} + {OFFSET}} \right) \times {GAIN}} \right)}{2048} \right\rbrack}}},} & (12.1)\end{matrix}$

where OFFSET corresponds with a zero offset of the surgical orientationdevice 12 determined during the calibration routine and GAIN correspondswith a ratiometric value determined during the calibration routine, withone GAIN value being used for negative tilt angles and a different GAINvalue being used for positive tilt angles.

Also at Block 1225, in arrangements where a dual-axis accelerometer isused, the electronic control unit 1102 can be configured to adjust thepitch angle (x axis) calculation to account for the mounting offsetangle (described above) of the dual-axis accelerometer relative to theouter housing 20 of the surgical orientation device 20. The result ofBlock 1225 is an absolute angle for each axis of rotation (e.g., pitch,roll) being monitored by the dual-axis accelerometer. The absolute pitchand roll angles can be used to calculate orientation measurements of thesurgical orientation device 12.

Orientation measurements for the surgical orientation device 12 can bedetermined based on a wide variety of reference frames in conjunctionwith any of a variety of surgical procedures.

In certain embodiments, calculations can be performed by softwaremodules executed by the electronic control unit 1102. In otherembodiments, the electronic control unit 1102 can generate measurementsusing data stored in one or more look-up tables (“LUT”s). In otherembodiments, other calculations can be derived based on the type ofsensor or sensors used, the procedure being performed, and/or thereference frame being employed. Specific calculations in accordance withother procedures are described, for example, in U.S. patent applicationSer. No. 12/509,388, filed Jul. 24, 2009, the contents of which areincorporated in their entirety by reference herein.

In certain embodiments, the electronic control unit 1102 can perform astabilization routine, process, or algorithm to assess or determine thestability, or reliability, of the calculated angle measurements. Forexample, the electronic control unit 1102 can keep a history of the last100 ms of calibrated sample data for each axis being monitored by thesensor(s) 40. Each time a new sample is added to the 100-sample history,a maximum and minimum value is determined for the 100-sample data set.The electronic control unit 1102 can then determine a delta differencebetween the maximum and minimum values. The electronic control unit 1102can then compare the delta difference between the maximum and minimumvalues to a threshold. If the delta difference is lower than thethreshold, then the data is considered to be stable and it is stored inmemory (e.g., external memory 1112) and time-stamped. If the deltadifference is greater than the threshold, then the data is considered tobe unstable. When retrieving an angle reading to display to the user,the electronic control unit 1102 can be configured to transmit the laststable data reading (assuming it is not too old) to the display 1110instead of the current unstable reading. If the last stable angleexceeds a time threshold, the unstable angle reading can be displayedalong with a visual indication notifying the user that the angle readingis unstable. For example, a red “shaky hand” icon or graphical userinterface image can be displayed on the display screen.

B. Orthopedic System for Measuring Distances in a Joint

With reference to FIGS. 3A and 3B, a orthopedic system 110 can be usedto measure distances in a joint. These distances can be measuredbetween, for example, a reference (e.g. reference post 14) and ananatomical landmark (e.g. a predetermined landmark such as the lessertrochanter). The distances can be measured both before a procedure aswell as after a procedure to determine whether the procedure has beensuccessful. The orthopedic system 110 can comprise the surgicalorientation device 12 described above, the reference post 14 describedabove (including, for example, sensor 15), a measuring device 112 and amarking device 118.

1. Device for Measuring Distances in a Joint

With continued reference to FIGS. 3A and 3B, the measuring device 112can comprise a structure or structures (e.g. an elongate structure)which facilitate measurement of a distance between the fixed referencepost 14 and an anatomical reference or references. The measuring device112 can comprise an angle assessment guide. The measuring device 112 canbe releasably coupled to the reference post 14. For example, themeasuring device 112 can comprise a coupling device 113 or otherstructure which connects the measuring device 112 to the proximal end 30of the reference post 14′. The measuring device 112 can include amarking or markings 114 along at least one side or portion. The markings114 can provide the user with visual evidence of the distance betweenthe fixed reference post 14 and the marking device 118.

The measuring device 112 can further include a hinge 115. The hinge 115can allow the measuring device 112, or a portion of the measuring device112, to be pivotably rotated relative to the reference post 14. In someembodiments, the measuring device 12 and marking device 118 can be bothpivotably rotated about the hinge 115, as well as rotated about thecoupling device 113. For example, the hinge 115 and coupling device 113can allow for rotational movement of the marking device 118 in both afirst plane, as well as a second plane orthogonal to the first plane.Thus, the measuring device 18 can be moved in at least two degrees ofrotational freedom.

In some embodiments, the marking device 118 can comprise a laser device.For example, a laser can be emitted from a marking device 118 and/ormeasuring device 112. The laser can contact and/or reference ananatomical location, and such location can be used to obtain ameasurement or measurements as described herein.

The measuring device 112 can further comprise an attachment structure116. The attachment structure 116 can releasably attach the surgicalorientation device 12 to the measuring device 112. The attachmentstructure 116 can comprise a coupling device or devices that allows thesurgical orientation device 12 and/or marking device 118 to moverelative to the measuring device 112. For example, in a preferredarrangement, when the reference post 14 is fixed into the patient's bonyanatomy, the surgical orientation device 12 and marking device 118 canslide longitudinally along a length of the measuring device 112, therebychanging the relative distance between the reference post 14 and themarking device 118. The attachment device 116 can further allow themarking device 118 to be moved generally through a range of elevationsso as to bring the marking device closer to or in contact with ananatomical landmark. As described above, the surgical orientation device12 can be configured to detect translational changes. Thus, both themarkings 114 and surgical orientation device itself can facilitate anaccurate measurement of a distance between the proximal end 30 ofreference post 14 and the marking device 118.

2. Device for Marking an Anatomical Landmark

With continued reference to FIG. 3B, the marking device 118 can comprisea pin or other structure which can be used to physically pinpoint and/orcontact an anatomical landmark. For example, and as described furtherherein, an end 120 of the marking device 118 can be brought into contactwith and/or placed adjacent the lesser trochanter, and the location onthe lesser trochanter can be marked with an ink or some other markingagent, such as for example a methylene blue marker. The marking device118 can be releasably coupled to the surgical orientation device 12,such that any movement of the surgical orientation device 12 causesidentical movement of the marking device 118. The marking device 118 canvisually indicate a position of an anatomical landmark during aprocedure. In certain embodiments, the marking device 118 can be a laserwhich projects a point of light down onto the anatomy without makingphysical contact or impairing access to or visualization of the jointspace. In certain embodiments a fan-style laser can be incorporated intothe system to be substantially in alignment with the measuring device112. The laser can be used as an aid to align an axis of the measuringdevice 112 (e.g. the “leg length” axis) with an axis of the leg byorienting the measuring device 112 such that the laser line passesthrough the center of the knee, ankle or other appropriate landmark.

C. Orthopedic System for Determining an Orientation of a Plane in aPatient's Anatomy

With reference to FIG. 4, an orthopedic system 210 can be used todetermine the orientation of an anatomical plane in the human anatomy,such as for example an anatomical plane defined by a landmark orlandmarks along the acetabular rim in a patient's pelvic area. Theorthopedic system 210 can comprise the surgical orientation device 12described above, and an anatomical contact device 214.

1. Anatomical Contact Device for Contacting a Landmark or Landmarks

With continued reference to FIG. 4, the anatomical contact device 214can comprise a hand-held and/or portable orthopedic device whichcomprises at least one component that contacts at least one anatomicallandmark on the patient's anatomy. For example, the anatomical contactdevice 214 can comprise an alignment handle 216 which is releasablycoupled to the surgical orientation device 12. The alignment handle 216can comprise a proximal end 217 with a handle, a distal end 219, and anelongate member 221 extending therebetween. The alignment handle 216 canbe gripped by a user's hand and moved, such that the handle 216 andsurgical orientation device 12 generally move together.

The anatomical contact device 214 can further comprise an anatomicalcontact component 218. The anatomical contact component 218 can comprisean acetabular landmark contacting device, and can be releasably coupledto the alignment handle 216, or can be integrally formed with thealignment handle 216. In a preferred arrangement, the component 218 cancomprise a tripod-like structure, with three arms 220 extending radiallyoutwardly from a center portion 222 of the component 218. Each of thethree arms 220 can be spaced radially equally from one another at 120degrees, although other arrangements are also possible, as are othernumbers of arms 220. Each of the arms 220 can further be angled suchthat no one plane contains any two of the arms 220. Each of the arms 220can comprise a tip 224. As described further herein, the tips 224 can beused to contact landmarks on the acetabular rim of the patient.

D. Orthopedic System for Preparing an Acetabular Surface

With reference to FIG. 5, an orthopedic system 310 can be used toprepare a portion of a patient's anatomy, such as for example anacetabular socket area in a patient's pelvis. The orthopedic system 310can be used, for example, to ream at a specified angle or orientationrelative to a reference and/or anatomical landmark. The orthopedicsystem 310 can comprise the surgical orientation device 12 describedabove, a protective mounting device 312, and a surface preparation tool314.

1. Stationary Mount for the Surgical Orientation Device

With continued reference to FIG. 5, the mounting device 312 can comprisea structure which releasably attaches to the surgical orientation device12 and allows the surgical orientation device 12 to generally remainstill while reaming takes place. For example, the protective mountingdevice 312 can comprise an elongate tubular structure and/or bearingwhich permits relative rotational movement of a structure within itsinner surfaces. The protective mounting device 312 can be made ofplastic, metal, or other suitable material. The mounting device 312 cancomprise lubricant applied to its inner surfaces, and/or can comprise abearing or bearings which inhibit the mounting device 312 from rotatingwhen reaming is taking place.

2. Acetabular Surface Preparation Device

With continued reference to FIG. 5, the surface preparation tool 314 cancomprise a device which can prepare a portion of a patient's anatomy.For example, the surface preparation tool 314 can ream out a portion ofa patient's acetabular socket. The surface preparation tool 314 cancomprise a reamer handle 316. The reamer handle 316, or a portion of thereamer handle 316, can extend through the mounting device 312, and atleast a portion of the reamer handle 316 can rotate relative to themounting device 312 while at least a portion of the surface preparationtool 314 is rotating. In some embodiments, the reamer handle 316 cancomprise a proximal end 317 that comprises a handle, a distal end 319,and a rotatable shaft portion 321 extending therebetween, the rotatableshaft portion 321 being rotatably coupled with the proximal end 317.

The surface preparation tool 314 can further comprise a surfacepreparation device 318. The surface preparation device 318 can bereleasably coupled or integrally formed with the reamer handle 316, andcan comprise a cutting tool or element which digs into and reams outbony matter and/or tissue in the patient's anatomy. For example, thesurface preparation device 318 can comprise a generally spherical-shapedcutting tool which is configured to ream out an acetabular socket.

E. Orthopedic System for Orienting a Prosthetic Hip Component

With reference to FIG. 6, a orthopedic system 410 can be used to orienta prosthetic component, such as for example a prosthetic acetabular cup.The orthopedic system 410 can be used to orient the prosthetic componentat a specified angle or orientation relative to a reference and/oranatomical landmark. The orthopedic system 410 can comprise, forexample, the surgical orientation device 12 described above, a guidedevice 412, and a prosthetic component 414 (e.g. prosthetic acetabularcup).

1. Device for Guiding a Prosthetic Component

With continued reference to FIG. 6, the guide device 412 can comprise aproximal end 416, a distal end 418, and an elongate portion 419extending therebetween. The proximal end 416 can comprise a handle thatcan be gripped by a user. The elongate portion 419 can comprise anelongate rod or structure which can be releasably coupled to thesurgical orientation device 12, such that the guide device 412 andsurgical orientation device 12 generally move together.

The distal end 418 can comprise a implant contacting structure whichreleasably couples the guide device 412 to the prosthetic component 414.While coupled, the prosthetic component 414 can move with the guidedevice 412. Once oriented, the prosthetic component 414 can be releasedfrom the guide device 412.

2. Prosthetic Component for Insertion in the Patient's Anatomy

The prosthetic component 414 can comprise any of a number of commonlyavailable prosthetics, including but not limited to prostheticacetabular cups. The acetabular cup size can vary depending upon thepatient. The prosthetic component 414 can be sized and shaped so as tofit into the area reamed out by orthopedic system 310.

III. HIP Preparation Methods

A number of different hip preparation methods are discussed below. Thesemethods can be used in conjunction with the systems described above, andare useful for modifying the natural hip joint to enable the hip jointto have a prosthetic component or components, such components includingbut not limited to a prosthetic acetabular cup.

A. Pre-Operative Planning

Prior to any hip procedure, a surgeon or other medical personnel cancreate templates of a patient's anatomy, and use these templates todetermine ideal post-procedure conditions within the patient's anatomy.For example, in a hip replacement procedure, the surgeon can firstobtain x-ray images of the patient's pelvis. Based on the images, thesurgeon can look at a diseased side of the hip, as well as the healthyside, and determine goals for joint offset and leg length.

FIG. 29A illustrates a joint offset prior to incising the capsule jointin the hip. As illustrated in FIG. 29A, joint offset (represented forexample by the arrows labeled “OS”) generally represents amedial/lateral component of the distance between two landmarks, one ofwhich is generally fixed. For example, during a hip replacementprocedure utilizing one or more of the systems described above, thereference post 14 can remain fixed. Thus, joint offset can berepresented by a distance “OS” between the fixed reference post 14 and aspecified landmark “A” on the femur, taken in a generally medial/lateraldirection.

Similarly, leg length can be represented by the arrows “LL” in FIG. 29A.With reference again to FIG. 29A, the leg length “LL” can be thecomponent of the distance between the fixed reference post 14 and thespecified landmark “A” on the femur, taken in a generallyproximal/distal direction perpendicular to that of the medial/lateraldirection.

When viewing the pre-operative x-rays, the surgeon can get an idea ofwhat changes in joint offset and leg length will be necessary on thediseased side of the hip to bring the hip into symmetry (e.g. both sidesof the hip having the same leg length and joint offset). If both sidesof the hip are not brought into symmetry, the joint offset on thediseased side of the hip can cause wear and deterioration of thesurrounding ligaments.

B. Establishing a Reference for Hip Replacement Using an OrthopedicSystem

With reference to FIG. 13, the orthopedic system 10 described above canbe used to establish a reference in the patient's anatomy. The referencecan be established prior to incising a joint capsule in the hip. Forexample, once the hip anatomy has been exposed by pulling backsurrounding tissue, the reference post 14 can be driven into a specifiedlandmark on the patient's anatomy. In one embodiment, such landmarkremains immobile throughout the rest of a hip replacement procedure.Thus, a landmark such as the iliac spine can be used, although otherlandmarks are also possible. For example, in some embodiments, asdiscussed in greater detail below, the reference post 14 can be driveninto a portion the femur, or other parts of the human anatomy. In someembodiments, the reference post 14 can be clamped and/or otherwiseanchored to a portion of the femur, and the pelvis can be referencedrelative to the femur.

Once a landmark is chosen, the surgeon can use a slap hammer or otherdevice to pound the impactor 16 and drive the reference post 14 into thepatient's anatomy as desired, until the reference post 14 is firmly inplace. If the reference post 14 has a sensor 15 on or embedded within orotherwise coupled to the reference post 14, the sensor 15 can be atleast partially within the bony mass of the pelvis (or other bony area),or can still be exterior of the anatomy after insertion of the referencepost 14. In some embodiments, the reference post 14 can comprise aretractor. For example, with the surrounding tissue pulled back, thereference post 14 can be configured as an anchor or as a retractor to atleast partially hold back the tissue that would normally be disposedabove or around the surgical site.

With reference to FIGS. 2A and 13, prior to the hip replacementprocedure, and prior to driving the reference post 14 into the iliacspine, the surgical orientation device 12 can be registered in aposition parallel to the operating table and floor. For example, dataabout the orientation of the surgical orientation device 12 can beobtained through the sensor or sensors 50 in the surgical orientationdevice 12 while the surgical orientation device is held parallel to theoperating table.

Once the surgical orientation device 12 is registered, and the referencepost 14 has been driven into the iliac spine, the pelvis can be adjustedand moved relative to a fixed reference frame. Because the angle adescribed above and shown in FIG. 2A can remain fixed relative to thereference post 14, movement of the system 10 and surgical orientationdevice 12 can be monitored. For example, in some embodiments thesurgical orientation device 12 can be positioned at a known angle, suchas an acute angle (e.g. 45 degrees), relative to a medial-lateral planeof the pelvic bone. In some embodiments, the surgical orientation device12 can be positioned at about 45 degrees relative to a longitudinal axisof the reference post 14. In some embodiments, the hip (with thereference post 14 inserted) can be adjusted until the surgicalorientation device 12 indicates an angle 90°-α, at which point thereference post 14 is positioned generally perpendicular to the floor,and the patient's pelvis is positioned generally parallel to the floor.Such positioning of the pelvis can be helpful, for example, in properpositioning of the prosthetic component 414 described above. In someembodiments, the reference post 14 can be driven vertically into theiliac spine while the patient is in a supine position. A probe, such asfor example a laser or mechanical rod, can be used to align the surgicalorientation device 12 with an axis of the leg to establish a referencerotation about a vertical axis and a direction for leg lengthmeasurement(s).

As described above, the reference post 14 can contain a sensor orsensors 15 that evaluate the orientation (e.g. position or angle) of thepelvis or other bony area. For example, once the pelvis has beenpositioned generally parallel to the operating table and floor, thesensor or sensors 15 can be zeroed and/or registered by the surgicalorientation device 12 or other device. In a preferred arrangement, thesensor 15 can communicate with the surgical orientation device 12,giving the surgical orientation device 12 information about theorientation of the iliac spine and/or pelvis. If the pelvis moves duringthe hip procedure, the surgical orientation device 12 can account forsuch movement since it has information about such movement from sensor15. Furthermore, the surgical orientation device 12 can additionallyobtain information about the spatial location of the reference post 14based on the sensor or sensors 15, and can use that information toobtain and record measurements of distance between the reference post 14and surgical orientation device 12. In some embodiments, the sensor 15can comprise a satellite sensor which communicates with the surgicalorientation device 12, and is separately read by the surgicalorientation device 12. In some embodiments, the surgical orientationdevice 12 and reference post 14 can each comprise a sensor or sensors.In some embodiments the surgical orientation device 12 can be configuredto only receive information from the sensor 15, and does not itself havean orientation sensor. Furthermore, in some embodiments, more than onesensor can be used. For example, the systems described herein cancomprise two or more sensors 15 located on the pelvis, greatertrochanter, and/or other anatomical landmarks.

In one embodiment, a first satellite sensor is the sensor 15 coupledwith the reference post 14, a second satellite sensor is coupled withanother surgical device, and both satellite sensors provide sensor datato a variation of the surgical orientation device 12. Where twosatellite sensors are provided, one can be coupled with a first boneadjacent to a joint and a second can be coupled with a second boneadjacent to a joint. With two satellite sensors, the position,orientation, or movement of these bones and the joint to which they areadjacent can be monitored.

With the reference post 14 thus positioned, the impactor 16, angleassessment guide 18, and surgical orientation device 12 can be removed,leaving only the reference post 14 behind. The reference post 14 canthen serve as a reference as described above, and can be used as ananchoring point for attachment of the orthopedic system 110.

FIGS. 13A and 13B show a technique in which the reference post 14 can becoupled with the patient's anatomy without being attached to any bonystructure. Rather, as shown in these figures, a fixture 510 is providedfor indirectly coupling the reference post 14 to the patient's anatomy.Although shown as providing for indirect coupling with a femur, thefixture 510 can be configured for attachment to other anatomy such thatthe reference post 14 does not need to be directly connected to bonystructure. This arrangement is useful where the clinician prefers not todisrupt the bony structure, such as where the bony structure is delicateor would be unduly weakened by such interaction.

In one embodiment, the fixture 510 includes a bone engagement portion514 that is configured to engage the bone in a static manner. Forexample, the bone engagement portion 514 can comprise a clampingstructure that generates sufficient normal force to provide securefrictional engagement with the femur or other anatomy. In someembodiments, the clamping structure is spring loaded or includes aratchet design to allow for quick attachment with sufficient force forimmobilizing the fixture 510.

The fixture 510 preferably also is configured to securely receive thereference post 14. For example, a mounting structure 518 can be coupledwith the bone engagement portion 514 and disposed laterally. The boneengagement portion 514 provides a surface area into which the referencepost 14 can be driven using a slap hammer or other device fortransmitting a force to the distal end of the reference post 14. Forexample, the impactor 16 can be coupled with the reference post 14, asdescribed herein, prior to driving the distal end of the reference post14 into the mounting structure 518. In other techniques, the distal endof the reference post 14 can be coupled with the mounting structure 518by clamping or other techniques that do not require applying a drivingforce, as with a slap hammer.

In the technique of FIGS. 13A, 13B, and 14A, the other orthopedicsystems described herein can be used during further aspects ofprocedures. For example, the angle assessment guide 18 can be used withthe surgical orientation device 12 in applying the reference post 14.This technique can be used in placing the reference post 14 when thefemur is positioned parallel to a surgical table. In some techniques,the femur is placed such that it is disposed generally perpendicular tothe direction of gravity prior to placement of the reference post 14, asshown in FIG. 13B.

FIG. 14A illustrates that after the reference post 14 has been placed,the measuring device 112 can be used to acquire information about thelocation of one or more anatomical landmarks. For example, the measuringdevice 112 can be used to locate a probe (e.g., a laser or mechanicalprobe or rod) above a landmark on the hip while the reference post 14 iscoupled with the femur. In particular, the measuring device 112 can becoupled with the reference post to provide for multiple degrees offreedom. For example, the measuring device 112 can be pivoted about alongitudinal axis of the reference post 14. In some embodiments, themeasuring device 112 is also tiltable about a second axis that isdisposed generally perpendicular to the longitudinal axis of thereference post 14, as described in connection with FIGS. 3A and 3B. Suchtilting may facilitate engagement with a wide variety of anatomicallandmarks on the hip by the marking device 118.

C. Measuring Joint Distances Using an Orthopedic System

With reference to FIGS. 3A-B and 14, prior to incising the jointcapsule, the orthopedic system 110 can be used to measure at least onedistance in the hip joint area. For example, the attachment structure116 of the measuring device 112 can be releasably coupled to thesurgical orientation device 12, and the measuring device 112 can becoupled to the fixed reference post 14. The measuring device 112 can bealigned with the axis of the leg so that measuring device 112 measuresthe leg-length component. The user can slide surgical orientation device12 and/or marking device 118 along the measuring device 112 until theend 120 of the marking device 118 is contacting a selected location orlocations on the femur (e.g., the superior aspect of the lessertrochanter), which location can then be marked with a suitablebiocompatible marker or other marking agent. The surgical orientationdevice 12, in a linear measurement mode, can then be zeroed, and canrecord a distance between the fixed reference post 14 and the anatomicallandmark or landmarks. In a preferred arrangement, the measurement ofdistance between the reference post 14 and marked location on theanatomical landmark can be obtained via communication between thesurgical orientation device 12 and the sensor 15 in reference post 14.The marking or markings 114 can provide an additional indication, of themeasured distance.

The surgical orientation device 12 can have two linear measurementcomponents, one which responds to leg length and one which responds tooffset. While the lesser trochanter is described in terms of ananatomical landmark, a different anatomical landmark or landmarks can beused instead, including but not limited to the greater trochanter. Inanother embodiment, a satellite tiltmeter can be attached to the femuron a location such as the greater trochanter which allows the angle ofthe femur to be zeroed and later reproduced when these measurements arerepeated at the trial reduction phase. This can eliminate small errorsin leg-length and offset which can be caused movement of the femur. Ifattached to the greater trochanter, this could be designed so that it isnot in the way during the procedure.

The distance between the reference post 14 and the superior aspect ofthe lesser trochanter can be correlated, or related to, anatomicaldistances such as leg length and joint offset as described above. Forexample, and as described above, such distance can be assessed by themedical provider in a pre-operative x-ray assessment. With reference toagain to FIG. 29A, end points of lines connecting the references pointsdescribed above can roughly correspond to a hypotenuse indicative of ananatomical distance, such that zeroing the surgical orientation device12 can result in the surgical orientation device registering this firstanatomical distance or distances as a reference distance(s). As usedherein “zeroing” is not limited by setting the SOD display to read “0”,but also includes, for example, recording a position in threedimensional space relative to a selected reference frame.

D. Determining the Orientation of an Anatomical Plane Using anOrthopedic System

With reference to FIGS. 15-18, once the orthopedic system 110 has beenused to measure a first reference distance or distances, the componentsof the system 110 other than the reference post 14 can be removed. Thejoint capsule can then be incised, and the proximal femur can beremoved. Once the proximal femur is removed, osteophytes surrounding theacetabular rim of the patient can also be removed according to knownprocedures.

With reference to FIGS. 4 and 19, the orthopedic system 210 can be usedto determine the orientation of an anatomical plane in the patient. Forexample, once the joint capsule has been incised and osteophytes havebeen removed, the alignment handle 216 can be releasably coupled to thesurgical orientation device 12. The alignment handle 216 can then begripped by the surgeon, and the anatomical contact component 218 can bemoved into contact with the acetabular rim. For example, the tripod-likestructure with arms 220, as shown in FIGS. 4 and 19, can be placedagainst the acetabular rim, and the tips 224 of the contact component218 can contact three landmarks on the acetabular rim. These threelandmarks can be determined by the surgeon or other user. Once threelandmarks have been contacted, the contact component 218 can bereferencing a plane extending across the acetabular rim. At this point,the surgeon can register the orientation of this plane with the surgicalorientation device 12. In some embodiments, a planar laser can project aline onto the pelvis of the patient. The surgeon can make a marksomewhere on this line which can be referenced in later steps. This canserve the purpose of establishing a reference rotational position of theorthopedic system about a vertical line. If rotation about a verticalaxis is not constrained in some form, then there can be an infinitenumber of orientations that satisfy a tiltmeter reading, since theirlocus can form a cone. Also, the surgical orientation device 12 canincorporate the orientation of the reference pin 14 in its calculationsso that the surgical orientation device 12 can compensate for anysubsequent movement of the pelvis.

In some embodiments, and as described herein, the surgical orientationdevice 12 can include a light indicator, such as a laser or lasers. Thelasers can be emitted from optical components 42 of the surgicalorientation device. Thus, in some embodiments of the orthopedic system110, the surgical orientation device, or other component, can emit alaser or lasers towards a landmark or landmarks in order to obtain anorientation of the acetabular rim. For example, the lasers can beemitted from the surgical orientation device such that they pinpoint anarea or areas along the acetabular rim, and provide an indication to thesurgical orientation device 12 of the orientation of a plane extendingacross the rim. In other embodiments, different landmarks can be used.

E. Preparing a Portion of the Patient's Anatomy Using an OrthopedicSystem

With reference to FIGS. 5 and 20, the orthopedic system 310 can be usedto prepare a portion of the patient's anatomy. For example, theorthopedic system 310 can be used to ream out an acetabular socket at adefined angle and/or orientation.

Once the orthopedic system 210 has established a reference plane, suchas for example the plane defined by the three reference landmarks on theacetabular rim, the reamer 318 can be moved into the area bounded by theacetabular rim. The surgeon can hold the reamer handle 316, and thereamer 318 and/or a portion or portions of the reamer handle 316 canspin and rotate. As the reamer 318 spins and digs into the bony area inthe acetabulum, the surgical orientation device 12 can remain generallystill while coupled to the mounting device 312. The surgeon can use thesurgical orientation device 12 to monitor the orientation of the reamer318. Thus, the surgeon can ream at a defined angle relative to theaforementioned reference plane, with the surgical orientation device 12providing an indication or indications on its display as to whether thereamer 318 is reaming perpendicular to such plane, or at an some anglerelative to the plane. In some embodiments, the surgeon can choose anappropriate angle based on pre-operative templates and/or a desiredrange of angles and movement for the implant 414.

F. Orienting a Prosthetic Component Using an Orthopedic System

With reference to FIGS. 6 and 21, the orthopedic system 410 can be usedto orient a prosthetic component, such as for example a prostheticacetabular cup. For example, the orthopedic system 410 can be used toorient a prosthetic component 414.

Once the orthopedic system 310 has been used to ream out an acetabularsocket, the orthopedic system 410 can be assembled. For example, thesurgical orientation device 12 can be releasably coupled to the handle416, and a prosthetic component 414 can be releasably coupled to thehandle 416. The surgeon can then hold onto the handle 416 and move theprosthetic component 414 (e.g. prosthetic acetabular cup) towards thereamed out acetabular socket. The surgical orientation device 12 can beused to monitor the orientation of the prosthetic component 414 as it ismoved and adjusted within the acetabulum. One can use a laser line (orother probe, such as for example a mechanical probe) to illuminate orotherwise reference a mark made earlier to control the rotation of thesurgical orientation device 12 about a vertical axis. One can also usethe orientation of the reference post 14 to compensate for movement ofthe pelvis. Once the prosthetic component 414 is positioned as desired(e.g. based on a pre-operative determination), the handle 416 andsurgical orientation device 12 can be removed.

In some embodiments, the orthopedic system 210 can then be used again toassess the orientation of the prosthetic component, as illustrated inFIG. 22. The anatomical contact component 218 can be placed against theprosthetic component 414, and the surgical orientation device 12 canindicate whether the prosthetic component 414 is oriented in the sameplane as that previously registered by the surgical orientation device,or whether there is some angular offset or offsets. For example, thesurgical orientation device 12 can indicate the prosthetic component 414is tilted at a five degree angle in one frame of reference relative tothe orientation of the reference plane previously registered by thesurgical orientation device and orthopedic system 210. As describedabove, such an offset may be advantageous or desired, depending on howthe surgeon wishes to orient the prosthetic. The system 210 can allowthe prosthetic component 414 to be aligned with the rim of theacetabulum as described above, or relative to the plane of the pelvis,whichever is preferred. In the latter case it can be unnecessary toregister the rim of the acetabulum.

G. Measuring Joint Distances Again Using an Orthopedic System

With reference to FIGS. 24-27, once a prosthetic component 414 has beenpositioned, joint distance(s) can be measured again. For example, oncethe prosthetic acetabular cup has been positioned, a femoral canal canbe formed, and a prosthetic femoral broach and head can be coupled tothe femur. Once the broach and head are coupled, the hip joint can bereduced and put back in place, with the prosthetic femoral head restinginside the prosthetic cup (e.g. prosthetic component 414).

With reference to FIG. 28, once the hip joint is reduced, the orthopedicsystem 110 can again be used to measure a distance from the fixedreference post 14 to an anatomical landmark (e.g. the same markedlocation on the superior aspect of the lesser trochanter).

With reference to FIG. 29B, this second reading can be compared with thefirst reading (e.g. the reading shown in FIG. 29A). Thus, a measurementor measurements can be taken both prior to joint capsule incision andafter joint reduction to determine whether there has been any change injoint offset “OS” and leg length “LL” in the patient's anatomy. If themeasurements are satisfactory for the surgeon, the prosthetic implantcan be left in. If not, the surgeon can remove the implant 414 and/oradjust the implant 414 using one or more of the systems described above,until desired measurements are obtained. In some embodiments thesurgical orientation device 12 can be programmed with a database ofgeometries of prosthetic components. The surgeon can input theconfiguration of components used in trial reduction plus his goals foradjusting offset and leg-length. The surgical orientation device 12 canthen perform calculations based on three-dimensional geometry todetermine a combination of components which should achieve his goals andrecommend them to the surgeon. This can take much of the trial and errorout of the process.

IV. Additional Sensors for Relative Movement

While the embodiments of the orthopedic systems and methods describedabove are described as having and using a sensor or sensors 50 locatedwithin the surgical orientation device 12, in some embodiments theorthopedic systems or other systems used for joint replacement caninclude an additional sensor or sensors 50 or 15. For example, and asdescribed above, the reference post 14 can include a sensor 15. Theseadditional sensors can be located on other surgical components and/oranatomical landmarks. U.S. Pat. No. 7,559,931 discloses examples ofsensors on multiple surgical components and/or anatomical landmarks, andis herein expressly incorporated by reference in its entirety. In someembodiments, the orthopedic systems can include an additional sensor orsensors on the femur, hip, or other anatomical locations. The additionalsensor can include a microcontroller and/or communication device (e.g.infrared or other wireless technology (e.g. Bluetooth™)) which can relayinformation from the additional sensor to the electronic control unit1102 of the surgical orientation device 12. This additional sensor orsensors can detect changes in movement of the patient's anatomy duringan orthopedic procedure, so as to verify whether the patient's anatomyhas moved or changed position during the procedure. In some embodiments,the sensor or sensors described herein (e.g. sensor 15) can be part of avariable capacitance system similar to that used in digital calipers.

The electronic control unit 1102 can be configured to receive theinformation from this additional sensor or sensors, and/or the sensor'scommunications device, and combine that information with informationfrom the sensor or sensors 50 located within the surgical orientationdevice 12 to calculate an overall, or aggregate, movement andorientation of the surgical orientation device 12 relative to, forexample, an axial line or plane. The electronic control unit 1102 cancorrect for changes in position of the surgical orientation device 12.

Additionally, the additional sensor or sensors can be located in adevice. The device can be constructed such that the device isautoclavable and reusable, and can allow insertion and removal of adisposable battery. The additional sensor or sensors can be incorporatedwith any of the systems and/or methods described herein, and can beplaced on any of the components of the systems described herein.

V. User Interfaces

The systems and methods described above can each incorporate the use ofa measuring device, such as for example the surgical orientation device12. As described above, the surgical orientation device 12 can compriseat least one user input, a display and an electronic control unit. Theuser inputs and display, and/or the combination of the inputs, display,and electronic control unit can together form part of an interactiveuser interface. For example, the interactive user interface can comprisea housing (e.g., housing 30 described above), a coupling member formedon or within the housing configured to removably couple the userinterface to an orthopedic device (e.g., handle 416), a sensor (e.g.,sensor 50 described above), an electronic control unit (e.g., electroniccontrol unit 1102 described above), a user input (e.g., user input 36described above, which can transmit input commands to the electroniccontrol unit), and a display (e.g., display 34 described above).

The interactive user interface can comprise a graphical user interfacehaving an interactive window displaying on-screen graphics. For example,the interactive user interface can provide the user with a plurality ofscreen displays. The screen displays can illustrate the steps to beperformed in a surgical procedure and can guide the user through theperformance of the steps. Each screen display can comprise one or moreon-screen graphics. The on-screen graphics can comprise one or morevisual cues or indicators to prompt the user as to what step or steps totake next during one of the procedural methods described above. Thevisual cues referenced herein can comprise instructive images, diagrams,pictoral representations, icons, animations, visual cues, charts,numerical readings, measurements, textual instructions, warnings (visualand/or audible), or other data. The interactive user interface can beconfigured to alter attributes (e.g., color) of the on-screen graphicsaccording to one or more data protocols. The interactive user interfacecan provide visual feedback to the user during performance of one ormore surgical procedures. In certain embodiments, the interactive userinterface can be configured to generate graphical user interface (“GUI”)images to be displayed to the user. As described above, the user caninteract with the surgical orientation device 12 via one or more userinput devices 1114 (e.g., buttons, switches, touchscreen displays,scroll wheel, track ball, keyboard, remote controls, a microphone inconjunction with speech recognition software). The interactive userinterface further can allow the user to confirm that a step has beencompleted (for example, by pressing a user input button). Theinteractive user interface can allow the user to enter data (e.g., anumerical value, such as a distance, an angle, and/or the like), verifya position of the surgical orientation device 12, turn a visiblealignment indication system on and off, and/or turn the entire surgicalorientation device on and off. In certain embodiments, the interactiveuser interface provides one or more drop-down lists or menus from whicha user can make selections. For example, the user can make selectionsfrom a drop-down list using a scroll wheel, trackball, and/or a seriesof button presses. In some embodiments, the user interface provides adrop-down list of predicates that dynamically updates based on userinput.

In at least one embodiment, a module for creating an interactive userinterface can comprise a computer readable medium having computerreadable program code embodied therein. The computer readable programcode can comprise a computer readable program code configured to displayone or more of a plurality of GUI images on a user interface of asurgical orientation device, the GUI images comprising instructiveimages related to the performance of a surgical procedure. The computerreadable program code can be configured to receive instructions from auser identifying the surgical procedure to be performed (e.g., whichjoint and/or right or left). The computer readable program code can beconfigured to show the user steps to be performed in the identifiedprocess for the identified surgical procedure. The computer readableprogram code can be configured to guide the user in performance of thesteps. For example, the computer readable program code can be configuredto receive from the user an instruction to continue to the next step inthe procedure, to receive orientation data from a sensor mounted withinthe surgical orientation device, and to display the orientation data onthe user interface of the surgical orientation device.

In at least one embodiment, the surgical orientation device 12 describedabove can comprise a display module configured to display informationand a sensor module configured to monitor the orientation of thesurgical orientation device 12 in a three-dimensional coordinatereference system, and to generate orientation data corresponding to themonitored orientation of the surgical orientation device. The surgicalorientation device 12 can further comprise a control module configuredto receive the orientation data from the sensor module and convert it toobjective signals for presentation on the display module, the controlmodule also configured to display a set of GUI images or other on-screengraphics on the display module, the GUI images or on-screen graphicsrepresenting the orientation data received from the sensor module andalso representing instructive images related to the performance of thejoint replacement surgery.

In at least one embodiment, the surgical orientation device 12 canreceive orientation data from a sensor module, receive input commandsfrom a user input module to store orientation data from a user inputmodule, convert the orientation data to a human readable format forpresentation on a display device, and display on the display deviceon-screen graphics or GUI images for communicating information to a userbased on the input commands and the orientation data, the informationcomprising instructive images for performing a joint replacement surgeryand one or more visual indicators of a current orientation of thedisplay device with respect to a fiducial, or reference, orientation.

In at least one embodiment, the surgical orientation device 12 describedherein can comprise a sensor module coupled to an alignment jig andconfigured to measure and record a fiducial orientation and tocontinuously collect orientation data of the surgical orientationdevice, a display module configured to display at least one visualindicator of the orientation of the surgical orientation device withrespect to the fiducial, or reference, orientation, the display modulefurther configured to display instructive images of one or more steps tobe performed by the surgeon during the joint replacement surgery, and acontrol module configured to receive the orientation data and to convertthe orientation data to objective signals for presentation on thedisplay module.

FIG. 30A-W show various screen shots which can form part of theinteractive user interface or interfaces described above. The screenshots can be seen, for example, on a display of the surgical orientationdevice 12.

As shown in FIG. 30A, an interface screen can illuminate requesting theuser to press a user input, e.g., a center button on the surgicalorientation device 12. Thereafter, a message can be displayed indicatingto the user that the surgical orientation device 12 is preparing foroperation. The message can be a display of text on a screen, asillustrated in FIG. 30A, an audible sound, or other signal to the userto wait for the device to confirm a proper operational state. Forexample, a variety of self-tests can be performed. In one embodiment,information about the operating system, such as its version, can bedisplayed for review.

FIG. 30B shows a user interface screen which indicates that a range ofpotential cup size templates are available. For example, the userinterface screen can indicate a “52” size.

FIG. 30C shows a user interface screen requesting the user to scrollthrough template options. For example, the user can press a side togglebutton to scroll through cup size template options.

FIG. 30D shows a user interface screen in which a user has selected a“48” size cup implant. The selection can be made by pressing a middlebutton below the display screen on the surgical orientation device 12.This selection of cup size can be based on a user's pre-operativeassessment of a patient.

FIGS. 30E-G show user interface screens similar to those of FIGS. 30B-D,in which a user can scroll through and select an appropriate stem sizetemplate.

FIG. 30H shows a user interface screen providing input to a user toattach the surgical orientation device 12 to the angle assessment guide18. The user can press a user input (e.g. an enter button) on thesurgical orientation device 12 to indicate completion of this step.

FIG. 30I shows a user interface screen providing input to a user toattach the reference post 14 to the impactor 16. The user can press auser input (e.g. an enter button) on the surgical orientation device 12to indicate completion of this step.

FIG. 30J shows a user interface screen providing information on theorientation of the system 10 to guide the user in proper orientationwhile the reference post 14 is impacted into patient.

FIG. 30K shows a user interface screen providing instructions to a userto attach the surgical orientation device 12 to the system 110. The usercan press a user input (e.g. an enter button) to indicate completion ofthis step.

FIG. 30L shows a user interface screen providing instructions to a userto attach the marking device 118 to the system 110. The user can press auser input (e.g. an enter button) to indicate completion of this step.

FIG. 30M shows a user interface screen providing instructions toestablish the position of the marking device 118 in system 110, with themarking device 118 referencing an anatomical landmark determined by theuser. Once the user has contacted the anatomical landmark, the user canpress a button (e.g. an enter button) to record an orientation of thesystem 110 with respect to that landmark.

FIG. 30N shows a user interface screen providing instructions to a userto prepare the acetabulum for cup implantation. The user can press auser input (e.g. an enter button) to indicate completion of this step.

FIG. 30O shows a user interface screen providing instructions to a userto attach the surgical orientation device 12 to the system 210. The usercan press a user input (e.g. an enter button) to indicate completion ofthis step.

FIG. 30P shows a user interface screen providing instructions to a userto assess a plane of the acetabulum. The user can press a user input(e.g. an enter button) to indicate completion of this step.

FIG. 30Q shows a user interface screen providing instructions to a userto ream the acetabulum using system 310, as well as providing feedbackto the user on the orientation of the reamer (with the surgicalorientation device 12 attached) so that user can use the reamer inaccordance with the plane established by acetabular lip assessmentguide. The user can press a user input (e.g. an enter button) toindicate completion of this step.

FIG. 30R shows a user interface screen providing instructions to a userto position a prosthetic cup 414 in the acetabulum. The user can press auser input (e.g. an enter button) to indicate completion of this step.

FIG. 30S shows a user interface screen providing instructions to a userto impact the prosthetic cup into the acetabulum using the system 410,as well as providing feedback to the user on the orientation of theprosthetic cup (with the surgical orientation device 12 attached) sothat the user can impact the cup in accordance with the planeestablished by the system 210. The user can press a user input (e.g. anenter button) to indicate completion of this step.

FIG. 30T shows a user interface screen providing instructions to theuser to fit a trial hip implant. The user can press a user input (e.g.an enter button) to indicate completion of this step.

FIGS. 30U, 30V show a user interface screen providing instructions tothe user to assess the orientation of the system 110 with respect to theanatomical landmark that was previously assessed by the marking device118 on the system 110. The user can measure the distance again from thereference post 14 to the landmark measure previously.

FIG. 30W shows a user interface screen displaying leg length and jointoff-set changes based on orientation changes of jigging system frominitial assessment of anatomical landmark in FIG. 13 and finalassessment in FIG. 22.

Although these inventions have been disclosed in the context of certainpreferred embodiments and examples, it will be understood by thoseskilled in the art that the present inventions extend beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the inventions and obvious modifications and equivalentsthereof. In addition, while several variations of the inventions havebeen shown and described in detail, other modifications, which arewithin the scope of these inventions, will be readily apparent to thoseof skill in the art based upon this disclosure. It is also contemplatedthat various combinations or sub-combinations of the specific featuresand aspects of the embodiments can be made and still fall within thescope of the inventions. It should be understood that various featuresand aspects of the disclosed embodiments can be combined with orsubstituted for one another in order to form varying modes of thedisclosed inventions. Thus, it is intended that the scope of at leastsome of the present inventions herein disclosed should not be limited bythe particular disclosed embodiments described above.

1. An apparatus for preparing a hip joint, comprising: a reference posthaving a distal end adapted to be driven into a portion of a pelvicbone, a proximal end, and a reference post body extending along alongitudinal axis between the proximal and distal ends; a couplingdevice disposed adjacent to the proximal end of the reference postadapted for connecting the reference post body to a second surgicalcomponent; and an orientation sensor coupled with the reference post. 2.The apparatus of claim 1, wherein the reference post body is adapted todisplace soft tissues disposed adjacent to the pelvic bone to at leastpartially expose the hip joint.
 3. The apparatus of claim 1, wherein thereference post is configured to facilitate axial alignment of thereference post and at least one other surgical component.
 4. Theapparatus of claim 1, wherein the coupling device comprises an annularrecess defined between a proximally facing shoulder and a distallyfacing shoulder.
 5. The apparatus of claim 4, further comprising animpactor having a fork-shaped member adapted to be received within theannular recess and to abut at least one of the proximal end of thereference post and the proximally facing shoulder to transfer a force tothe reference post body.
 6. The apparatus of claim 1, further comprisingan impactor having a distal end, a proximal end, and a rigid memberextending therebetween, the distal end of the impactor adapted to dockwith the coupling device such that a force applied to the proximal endof the impactor can be transferred to the distal end of the referencepost.
 7. The apparatus of claim 6, further comprising: an angleassessment guide configured to couple with the proximal end of theimpactor at a selected angular orientation relative to the referencepost; and a surgical orientation device configured to couple with theangle assessment guide.
 8. The apparatus of claim 7, wherein thesurgical orientation device is adapted to receive input from theorientation sensor coupled with the reference body.
 9. The apparatus ofclaim 7, further comprising a coupling device for mounting the surgicalorientation device to the angle assessment guide.
 10. The apparatus ofclaim 7, wherein the angle assessment guide comprises: a first elongatemember adapted to couple with the proximal end of the impactor; a secondelongate member coupled with the first elongate member at a first endand disposed at an angle relative to the first elongate member; and athird elongate member mounted to the second elongate member at a secondend thereof, the third elongate member being oriented at substantiallyparallel to a plane including the longitudinal axis of the referencepost body.
 11. An apparatus for preparing a hip joint, comprising: amounting structure having a first end adapted to secure to a patient'sanatomy and a second end disposed away from the first end; an elongatemember having a first end and a second end, the first end of theelongate member adapted to connect to the second end of the mountingstructure; a marking device coupled with the second end of the elongatemember for visually indicating the position of an anatomical landmarkduring a procedure; and a surgical orientation device coupled with theelongate member for movement therealong for measuring at least one ofposition and orientation along the elongate member.
 12. The apparatus ofclaim 11, further comprising gradation markings along the elongatemember for providing indications of measurement.
 13. The apparatus ofclaim 11, wherein the marking device is a laser device.
 14. Theapparatus of claim 11, further comprising a first coupling deviceconfigured to adjustably position the marking device along a range ofpositions along the elongate member such that the marking device can bepositioned above an anatomical landmark adjacent to a hip joint.
 15. Theapparatus of claim 14, further comprising a second coupling deviceconfigured to adjustably position the marking device along a range ofelevations below the elongate member such that the marking device can bebrought into contact with an anatomical landmark adjacent to a hipjoint.
 16. The apparatus of claim 15, further comprising a thirdcoupling device for connecting the elongate member to the second end ofthe mounting structure, such that the elongate member is permitted to bepositioned about an axis extending through the mounting structure. 17.The apparatus of claim 11, wherein the mounting structure is configuredto be driven into an anatomical landmark on a patient's pelvis, theelongate member is of sufficient length to be positioned over ananatomical landmark on the patient's femur, and the marking device isconfigured to provide visible indication of the anatomical landmark onthe patient's femur.
 18. The apparatus of claim 17, wherein the mountingstructure has an orientation sensor coupled therewith.
 19. The apparatusof claim 17, wherein the anatomical landmark on the patient's pelvis isthe iliac spine.
 20. The apparatus of claim 17, wherein the anatomicallandmark on the patient's femur is the lesser trochanter.
 21. Anapparatus for assessing the orientation of an acetabular landmark or anacetabular implant, comprising: a handling device comprising a proximalend with a handle, a distal end, and an elongate member extendingtherebetween; an acetabular landmark contacting device coupled with thedistal end of the handling device; and a surgical orientation device fordetecting and recording an orientation of the acetabular landmark or theacetabular implant.
 22. The apparatus of claim 21, wherein theacetabular landmark contacting device comprises three elongate contactmembers extending away from the distal end of the handling device atequal angles relative to each other.
 23. An acetabular surfacepreparation apparatus, comprising: a handling device comprising aproximal end with a handle, a distal end, and a rotatable shaftextending therebetween; a surface preparation device coupled with thedistal end and adapted to remove bone from the acetabulum to create asurface suitable for receiving an acetabular implant; a sleeve disposedaround the rotatable shaft and adapted to remain stationary while theshaft is rotating; and a surgical orientation device coupled with thesleeve such that the orientation device can remain stationary while therotatable shaft is rotated.
 24. The acetabular surface preparationapparatus of claim 23, wherein the surface preparation device comprisesa reamer.
 25. An acetabular implant placement device, comprising: ahandling device comprising a proximal end with a handle, a distal end,and an elongate member extending therebetween, wherein the distal endcomprises an implant contacting structure adapted to couple with anacetabular implant; and a surgical orientation device coupled with thehandling device such that the orientation of at least one of thehandling device and the surgical orientation device can be monitored asthe acetabular implant is advanced into the acetabulum.
 26. Theacetabular implant placement device of claim 25, further comprising afixed orientation sensor adapted to provide orientation informationabout the patient independent of the surgical orientation device. 27.The acetabular implant placement device of claim 25, wherein thesurgical orientation device is adapted to receive the orientationinformation from the fixed position sensor. 28-57. (canceled)